linux-kernel - Re: [PATCH] regulator: lochnagar: Fix n

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Message-ID: <20190129095438.GJ3837@imbe.wolfsonmicro.main>
Date:   Tue, 29 Jan 2019 09:54:38 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Axel Lin <axel.lin@...ics.com>
CC:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] regulator: lochnagar: Fix n_voltages setting for VDDCORE

On Tue, Jan 29, 2019 at 11:01:56AM +0800, Axel Lin wrote:
> With current n_voltages setting, regulator_list_voltage will return
> -EINVAL when selector >=57. The highest selector is 0x41, so the
> n_voltages should be 0x41+1, i.e. 66.
> 
> Signed-off-by: Axel Lin <axel.lin@...ics.com>
> ---
>  drivers/regulator/lochnagar-regulator.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/regulator/lochnagar-regulator.c b/drivers/regulator/lochnagar-regulator.c
> index 4962d13659aa..ff97cc50f2eb 100644
> --- a/drivers/regulator/lochnagar-regulator.c
> +++ b/drivers/regulator/lochnagar-regulator.c
> @@ -194,7 +194,7 @@ static const struct regulator_desc lochnagar_regulators[] = {
>  		.name = "VDDCORE",
>  		.supply_name = "SYSVDD",
>  		.type = REGULATOR_VOLTAGE,
> -		.n_voltages = 57,
> +		.n_voltages = 66,
>  		.ops = &lochnagar_vddcore_ops,
>  
>  		.id = LOCHNAGAR_VDDCORE,
> -- 
> 2.17.1

Hmm... I think this might need a little more investigation, it
does indeed fail at present (amazing that it works upto exactly 1.2V
which is common the usecase) but this feels more like a core
problem. There are indeed only 57 valid voltage settings as the
range is 0x8 - 0x41, but it seems that presently the core treats
this less as n_voltages and more like max_selector. Should we
perhaps be teaching the core to understand the min_selector
instead?

Thanks,
Charles